Abstract

Organic compounds from marine organisms have extensively studied in the traitment of many diseases and serve as compounds of interest both in their natural form and as templates for synthetic modification. Over 15,000 novel compounds have been chemically determined since 1975. Focusing on bioproducts,recent trends in drug research from natural sources suggest that algae are a promising group to furnish novel biochemically active substances[1]. Halogenated compounds are naturally produced by brown algae and are dispersed in several different classes of primary and secondary metabolites including carbohydrates,terpenes and polyphenolic compounds as predominant metabolite classes. New promising phloroglucinol derivatives[2] and bisnorditerpene[3] are extracted from the scytosiphonaceae macroalgae secondary metabolites with potent activity inantioxydant and anticancer research. Our study has focused on the abundant brown alga[4] Chnoospora minima (Scytosiphonales) collected in French Polynesia Island. Radical scavenging/antioxydant activities of differents extracts with a mixture of methanol/demineralized water (50/50,V/V) were assessed using the DPPH (2,2-diphenyl-16picrylhydrazil) free-radical method. The antioxydant activity seems to depend on the degree of depolymerisation of phloroglucinol, small sulfated phlorotannins being more active generaly than highly polymerised compounds. The cytotoxic and pro-apoptotic effects of crude extracts and their fractions from C. minima have been examined on several human cell lines : Jurkat (leukaemia T cell), Daudi (Burkitt lymphoma, B cell). Two crude extracts (CH2CL2 and CHCL3) have demonstrated a rapid cell death in all these cell lines, revealed by Annexine V+/IP+ staining in flow cytometry. Apoptosis induced by 100 µg of these extracts was accompanied by exposure of membrane phosphatidylserines and caspases activation in all cells lines. Preliminary analyses have suggested that is probably the terpenes compounds from C. minima extracts that induced cytotoxic effects and apoptose in human cancer cell lines.